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Re: #144: Attacks from Same Host (OppSec)

From: Kari Hurtta <hurtta-ietf@elmme-mailer.org>
Date: Wed, 02 Mar 2016 17:15:02 +0000
To: HTTP WG <ietf-http-wg@w3.org>, Mark Nottingham <mnot@mnot.net>
Cc: Kari Hurtta <hurtta-ietf@elmme-mailer.org>
Message-Id: <201603021714.u22HEQR4015020@shell.siilo.fmi.fi>
Kari Hurtta <hurtta-ietf@elmme-mailer.org>: (Wed Mar  2 19:02:46 2016)
> 
> | 3. Server Authentication
> | 
> | [I-D.ietf-httpbis-alt-svc] Section 2.1requires that an alternative
> | service only be used when there are "reasonable assurances" that it is
> | under control of and valid for the whole origin
> | 
> | For the purposes of this specification, there are two ways to achieve
> | this:
> | 
> | • Using TLS with a certificate that validates as per [RFC2818], or
> | • Confirming that both the origin and the alternative service support
> | this specification by obtaining a 200 (OK) response for the "http-tls"
> | well-known URI (section X).
> | 
> | The latter approach allows deployment without the use of valid
> | certificates, to encourage deployment of opportunistic security.
> | Therefore, in these cases the alternative service can provide any
> | certificate, or even select TLS cipher suites that do not include
> | authentication.
> 
> 1) This seems not specify that alternative is same host than
>   origin in case when valid certificate is not required
> 
> There fore "http-tls" well-known URI on _alternative_
> must include origin -name (method, host, port)

I note that perhaps that part 1) is handled with
421 Misdirected Request HTTP Status Code

But I think that it is still good idea include
origin to "http-tls" well-known URI.


> 2) If origin does not filter Alt-Svc: -headers, 
>   http://origin/~attacker/  skript can still
>   produce 
>      Alt-Svc: h2=":8000"
> 
>  and if origin runs it own real alternative on port 81
>  then it will have "http-tls" well-known URI
> 
> There fore "http-tls" well-known URI on _origin_
> must include alternative (host and port).
> 

Of course filtering Alt-Svc: on user suplied 
scripts handles this.

But I think that it s still good idea include
alternative host / port to "http-tls" well-known URI.

> 
> Because it is alternative 
> "http-tls" well-known URI on _origin_ and _alternative_
> must be same.
> 
> Therefore "http-tls" well-known URI must include
> origin -name and alternative (host and port).
> 
> Now comments about format of "http-tls" well-known URI
> except that it should be something what can
> not be silently truncated.

/ Kari Hurtta
Received on Wednesday, 2 March 2016 21:36:28 UTC

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